This invention relates generally to mine doors, and more particularly to a mine door system for installation in a passageway in a mine.
Mine doors are widely used to block air flow yet allow passage through passageways in mines, and to further act as fire barriers. Many such doors are difficult and time-consuming to install; and many cannot be readily adjusted to fit passageways of varying dimension. Moreover, existing mine doors often fail to provide a substantially air-tight seal to block the flow of air through a mine passageway, especially if the door is displaced due to convergence of the walls and/or ceiling of the passageway.
Existing mine doors, such as disclosed in co-assigned U.S. Pat. No. 4,911,577, are closed and opened manually. There is presently a need to provide a power operated mine door. For reasons of safety, such a power mine door should preferably be equipped so that it cannot apply undue opening or closing forces against an object (e.g., a person) in its path.
It is occasionally desirable to access a mine passage blocked-off by a mine door without opening the mine door. The provision of a smaller door, which is referred to as a man door, permits such access. However, such a door may be difficult to open when there is a substantial pressure difference on opposite sides of the door.